A virtual tape library (VTL) is a data storage virtualization technology used typically for data backup and recovery purposes. A VTL presents a storage component (usually hard disk storage) as tape libraries or tape drives for use with existing backup software. Virtualizing the disk storage as tape allows integration of VTLs with existing backup software and existing backup and recovery processes and policies. The benefits of such virtualization include storage consolidation and faster data restore processes. Some current VTL solutions use SAS (Serial Attached (Small Computer System Interface (SCSI)) or SATA (Serial AT Attachment) disk arrays as a storage component due to their relatively low cost. The use of array enclosures increases the scalability of the solution by allowing the addition of more disk drives and enclosures to increase the storage capacity. The shift to VTL also eliminates streaming problems that often impair efficiency in tape drives as disk technology does not rely on streaming, and hence can write effectively regardless of data transfer speeds. By backing up data to disks instead of tapes, VTL increases performance of both backup and recovery operations.
While a virtual tape library is fast, the disk storage within is not designed to be removable, and does not usually involve physically removable external disk drives to be used for data archiving in place of tape. Since the disk storage is connected to power and data sources and is not physically isolated, it is vulnerable to potential damage or data corruption. Further, the VTL system is typically statelful. This means that when a failure occurs during the VTL system backup process, the backup process for the data needs to be restarted after system recovery.
S3 is another storage technology by Amazon™ for the Internet. It is a storage service that offers software developers a scalable, reliable, and low-latency data storage infrastructure at relatively low cost. S3 storage technology provides a web service interface that can be used to store and retrieve data, at any time, from anywhere on the web (the Internet). Using this web service, developers can build applications that make use of Internet storage. Since S3 is scalable, developers grow their S3 based applications as desired, without compromising on performance or reliability. S3 technology is flexible in terms of allowing the storing of different types and amounts of data, reading the same data as many times as needed and for emergency recovery, and building File transfer Protocol (FTP) or other web applications. S3 also offloads regulatory compliance requirements to service providers.